sync further changes from uts/aslr

@@ -60,32 +60,41 @@
 #include <vm/seg_vn.h>
 
 int use_brk_lpg = 1;
 int use_stk_lpg = 1;
 
+/*
+ * If set, we will not randomize mappings where the 'addr' argument is
+ * non-NULL and not an alignment.
+ */
+int aslr_respect_mmap_hint = 0;
+
 static int brk_lpg(caddr_t nva);
 static int grow_lpg(caddr_t sp);
 
 intptr_t
 brk(caddr_t nva)
 {
         int error;
         proc_t *p = curproc;
 
         /*
-         * As a special case to aid the implementation of sbrk(3C), if given a
-         * new brk of 0, return the current brk.  We'll hide this in brk(3C).
-         */
-        if (nva == 0)
-                return ((intptr_t)(p->p_brkbase + p->p_brksize));
-
-        /*
          * Serialize brk operations on an address space.
          * This also serves as the lock protecting p_brksize
          * and p_brkpageszc.
          */
         as_rangelock(p->p_as);
+
+        /*
+         * As a special case to aid the implementation of sbrk(3C), if given a
+         * new brk of 0, return the current brk.  We'll hide this in brk(3C).
+         */
+        if (nva == 0) {
+                as_rangeunlock(p->p_as);
+                return ((intptr_t)(p->p_brkbase + p->p_brksize));
+        }
+
         if (use_brk_lpg && (p->p_flag & SAUTOLPG) != 0) {
                 error = brk_lpg(nva);
         } else {
                 error = brk_internal(nva, p->p_brkpageszc);
         }

@@ -593,10 +602,13 @@
         vn_a.lgrp_mem_policy_flags = 0;
 
         return (as_map(as, *addrp, len, segvn_create, &vn_a));
 }
 
+#define RANDOMIZABLE_MAPPING(addr, flags) (((flags & MAP_FIXED) == 0) && \
+        !(((flags & MAP_ALIGN) == 0) && (addr != 0) && aslr_respect_mmap_hint))
+
 static int
 smmap_common(caddr_t *addrp, size_t len,
     int prot, int flags, struct file *fp, offset_t pos)
 {
         struct vnode *vp;

@@ -627,11 +639,11 @@
 
         /*
          * If it's not a fixed allocation and mmap ASLR is enabled, randomize
          * it.
          */
-        if (((flags & MAP_FIXED) == 0) &&
+        if (RANDOMIZABLE_MAPPING(*addrp, flags) &&
             secflag_enabled(curproc, PROC_SEC_ASLR))
                 flags |= _MAP_RANDOMIZE;
 
 #if defined(__sparc)
         /*